As research in ad hoc networking has advanced, the importance of security increases more and more. But it suffers from the restriction that ad hoc networks do not have the established infrastructure. In this paper we propose a security-enhanced model with ID-based cryptosystem which removes the necessity for any infrastructure and provides sound authentication. Also we provide a more secure and concrete routing protocol with aggregate signature. For confidentiality, we also provide a key exchange protocol. And our model not only distributes the role of key generation center in ID-based cryptosystem to the nodes with threshold cryptography, but also increases availability by providing a secret re-sharing protocol. Therefore, our model is very appropriate for ad hoc networks. Copyright (c) 2007 John Wiley & Sons, Ltd.